Lasers are used in a variety of applications to transmit data. For example, lasers can be used in passive optical networks (PONs), such as gigabit PONs (GPONs) and 10 G PONs (XGPONs). A PON is a point-to-multipoint network architecture comprising an optical line terminal (OLT) at the service provider and ONUs at subscribers for providing the subscribers broadband services. A laser can be implemented, for example, at each ONU at the subscriber station. A laser driver can also be implemented at each ONU to drive the laser with the data the laser transmits.
Lasers can transmit data in a variety of modes. For example, in burst mode, the laser driver modulates data so the laser transmits data repeatedly without waiting for input from another device or waiting for an internal process to terminate before continuing the transfer of data. Laser drivers are expected to transmit whatever data is on the transmit data pins while a burst enable signal is in the “transmit” state and not to transmit the content of the data on its data pins otherwise, and laser drivers generally expect a short period of time between burst “off” and “on” states. The data pins will always have a data signal (or other signal intended to maintain switching over the pins). Laser drivers are usually not assumed to know when the data on the data pins is not being used to transmit meaningful data. Because of the above considerations and because the deciphering of the transmission allocation map is part of the Media Access Control (MAC) functionality, the laser driver itself cannot accurately predict whether it has enough time to power down internal circuitry to save power when the laser driver is not transmitting data. Thus, the laser driver dissipates approximately the same amount of power regardless of whether the laser is transmitting meaningful data. This leads to inefficiencies in power usage.
Methods and systems are provided for implementing an efficient power control scheme in a laser driver so that power is conserved when the laser is not being used to transmit meaningful data.
Features and advantages of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.